What constitutes a "hazardous substance" in relation to USTs?

A "hazardous substance" is defined as any chemical or material that poses a substantial threat to public health or the environment. This definition encompasses a broad range of substances that, due to their chemical nature or concentration, can have harmful effects if released into the environment. The regulatory framework surrounding underground storage tanks (USTs) is designed to protect the public and the environment from the potential dangers posed by these materials.

In the context of USTs, hazardous substances include not only petroleum products but also a variety of other chemicals that may be stored in such tanks. Their potential to contaminate soil, groundwater, and surface water necessitates strict monitoring and management practices. Recognizing a substance as hazardous allows regulatory agencies to impose necessary safety protocols and remediation measures, ensuring that both human health and environmental integrity are maintained.

The other choices do not align with the regulatory definitions of hazardous substances. For instance, defining hazardous substances as materials that are safe for the public contradicts the core concept of a hazardous substance. Similarly, limiting the definition only to petroleum products excludes many other harmful chemicals that can also be stored in USTs. Lastly, referring to materials that are non-toxic and biodegradable fails to acknowledge that even some biodegradable materials can be hazardous under certain conditions,